It is generally desirable for the operator of a vehicle such as an agricultural tractor or a highway mower to sit level relative to the horizontal while operating the vehicle. Afflictions such as fatigue, back pain and the like can result if the operator is made uncomfortable due to an unlevel seat. Sustained operation of the vehicle over inclined areas, such as mowing the grassy banks adjacent limited access highways, can quickly lead to these afflictions when the operator sits on a seating surface that is generally parallel with incline d terrain over which the vehicle is travelling. Moreover, the operator of a vehicle travelling across an inclined terrain is less able to maintain safe control of the vehicle and/or preclude contributing to a vehicle roll-over if he or she is not seated in a generally upright orientation.
Various tiltable seat mounting structures that maintain a vehicle seat level with respect to the horizontal are known. Examples of such known tiltable seat mounting structures are disclosed in U.S. Pat. Nos. 5,372,347; 4,515,337; 4,500,062; 4,183,492; 4,095,770; 3,970,274; 4,466,089 and 1,640,812. While these prior devices meet some of the objectives for a horizontally tiltable vehicle seat, they have not completely met the objectives or the requirements for such a seat, and are thus known to have shortcomings. Examples of such shortcomings include, but are not limited to, complexity in design, being cumbersome to operate, offering limited tiltability, being relatively expensive and being expensive to manufacture. Therefore, a self-levelling seat structure that overcomes shortcomings associated with conventional self-levelling seat structures would be advantageous, desirable and useful.